The present disclosure generally relates to fluid systems, including microfluidic devices, systems that include such devices, and methods that use such devices and systems. More particularly, the present disclosure relates to devices, systems, and methods for generating functional biological material, substances, or agents based on biomimetic platforms.
Blood platelets (PLTs) are essential for hemostasis, angiogenesis, and innate immunity, and when numbers dip to low levels, a condition known as thrombocytopenia, a patient is at serious risk of death from hemorrhage. Some causes for low platelet count include surgery, cancer, cancer treatments, aplastic anemia, toxic chemicals, alcohol, viruses, infection, pregnancy, and idiopathic immune thrombocytopenia.
Replacement PLTs to treat such conditions are generally derived entirely from human donors, despite serious clinical concerns owing to their immunogenicity and associated risk of sepsis. However, the shortages created by increased demand for PLT transfusions, coupled with near-static pool of donors and short shelf-life on account of bacterial testing and deterioration, are making it harder for health care professionals to provide adequate care for their patients. Moreover, alternatives such as artificial platelet substitutes, have thus far failed to replace physiological platelet products.
In vivo, PLTs are produced by progenitor cells, known as megakaryocytes (MKs). Located outside blood vessels in the bone marrow (BM), MKs extend long, branching cellular structures (proPLTs) into sinusoidal blood vessels, where they experience shear rates and release PLTs into the circulation. While functional human PLTs have been grown in vitro, cell culture approaches to-date have yielded only about 10 percent proPLT production and 10-100 PLTs per human MK. By contrast, nearly all adult MKs in humans must produce roughly 1,000-10,000 PLTs each to account for the number of circulating PLTs. This constitutes a significant bottleneck in the ex vivo production of platelet transfusion unit. Although second generation cell culture approaches have provided further insight into the physiological drivers of PLT release, they have been unable to recreate the entire BM microenvironment, exhibiting limited individual control of extracellular matrix (ECM) composition, BM stiffness, endothelial cell contacts, or vascular shear rates; and have been unsuccessful in synchronizing proPLT production, resulting in non-uniform PLT release over a period of 6-8 days. Moreover, the inability to resolve proPLT extension and release under physiologically relevant conditions by high-resolution live-cell microscopy has significantly hampered efforts to identify the cytoskeletal mechanics of PLT production to enable drug development and establish new treatments for thrombocytopenia. Therefore, an efficient, donor-independent PLT system capable of generating clinically significant numbers of functional human PLTs is necessary to obviate risks associated with PLT procurement and storage, and help meet growing transfusion needs.
Considering the above, there continues to be a clear need for devices, systems, and methods employing platforms that can recapitulate vascular physiology to accurately reflect the processes, mechanisms, and conditions influencing the efficient production of functional human blood platelets. Such platforms would prove highly useful for the purposes of efficiently generating human platelets for infusion, as well as for establishing drug effects and interactions in the preclinical stages of development.